Author: Robert Hyatt
Date: 11:33:05 10/08/02
Go up one level in this thread
On October 08, 2002 at 13:26:52, Uri Blass wrote: >On October 08, 2002 at 13:16:22, Robert Hyatt wrote: > >>On October 08, 2002 at 12:22:30, Uri Blass wrote: >> >>>On October 08, 2002 at 12:10:41, Robert Hyatt wrote: >>> >>>>On October 08, 2002 at 10:55:29, Uri Blass wrote: >>>> >>>>>On October 08, 2002 at 10:50:20, Robert Hyatt wrote: >>>>> >>>>>>On October 08, 2002 at 07:08:51, Uri Blass wrote: >>>>>> >>>>>>>On October 08, 2002 at 00:52:38, Eugene Nalimov wrote: >>>>>>> >>>>>>>>Wrong. >>>>>>>> >>>>>>>>Today I visited the talk by Feng-Hsiung Hsu he gave at Microsoft. Here are some >>>>>>>>points from memory: >>>>>>>> >>>>>>>>They used forward pruning in the hardware, and according to Hsu it gives them >>>>>>>>5x-10x speedup. He wrote about that in the book, too, but without any details. >>>>>>> >>>>>>> >>>>>>>Can you ask him if 12(6) really means 12 plies in the software and 6 plies in >>>>>>>the hardware? >>>>>>> >>>>>>>A second question is if the plies in the hardware were selective search from the >>>>>>>first ply. >>>>>>> >>>>>>>>In the talk he named that pruning as "analogy cutoff" and mentioned that "if the >>>>>>>>move is useless in some position, it is also useless in the similar position". >>>>>>>>In the book he writes "it can be done in the hardware as long as it does not >>>>>>>>have to be 100% correct". >>>>>>>> >>>>>>>>They used null-move thread detection, as well as not only singular extension, >>>>>>>>but also extension on only 2 or 3 good replies. They used fractional extensions. >>>>>>>>He also says that their Q-search is much more powerful than the one that is >>>>>>>>usually used in the software-only programs. >>>>>>>> >>>>>>>>Hsu gave some details why they don't use null-move: >>>>>>>>(1) He thinks that singular extensions and null-move gave more-or-less the same >>>>>>>>rating difference (100-200 points IIRC). >>>>>>> >>>>>>>I think that he underestimates null-move pruning. >>>>>>> >>>>>>>I believe that for long time control null move pruning gives more than 100-200 >>>>>>>points. >>>>>>> >>>>>>>People may try Fritz with selectivity=0 to find it's rating without null move. >>>>>>> >>>>>>>Uri >>>>>> >>>>>> >>>>>>I can assure you it doesn't. Several of us ran this experiment in the past. It >>>>>>produced a 50-100 >>>>>>point improvement at most. Bruce ran it first. I then repeated it to see if >>>>>>his result held for me >>>>>>as well. 50-100 is nothing to sneeze at of course... But that is all it will >>>>>>give... >>>>> >>>>>What was the time control and the hardware. >>>>> >>>>>I believe that the improvement is bigger >>>>>at slower time control. >>>>> >>>>>If the experiment was some years ago and >>>>>in time control that is faster than 120/40 >>>>>then the results may be different today. >>>>> >>>>>Uri >>>> >>>> >>>>I don't know about Bruce. I used 40 moves in one hour followed by 20 moves in >>>>30 minutes, >>>>with no sudden-death at all. >>>> >>>>I ran it on several computers here for several weeks... >>> >>>We have a factor of 2 in the time control. >>> >>>What was the hardware that was used? >>>If the games were played 5 years ago then today we have clearly >>>faster hardware. >>> >>>Uri >> >> >>Pentium pro 200's. I played 2 games at a time on my quad, plus more games in a >>linux lab we >>had set up. >> >>yes hardware is faster. No I don't believe that going deeper and deeper >>eliminates all the problems >>with null-move. I only saw bad problems at depths of 5-6-7-8. I _never_ saw >>them pop up at >>depths of 12 and beyond, which Crafty could reach in the pentium pro at 1 minute >>a move... >> >>R=2 used to gain at most 2 plies. Yet the overall performance improvement from >>my testing >>was in the 50-60 point range. Far less than what you would normally expect from >>gaining 2 >>plies. The conclusion? You aren't _really_ gaining two plies of search depth, >>just two plies >>reported in the output... > >I did not say that you get 2 plies of search depth from 2 plies of output but >only that I believe that the difference is bigger than 100-200. > >It may be interesting to repeat the experiment today >(you use R=2/3 and not R=2 and it is also important). > >Uri OK... that means that you think that a null-mover will win 3 of every 4 games vs a non-null-mover, _everything_ else being the same? I can run that test. I'll let you pick the time control. Pick something that xboard/winboard will like and I'll fire it up on a quad and let it play two games at a time using one processor for each side) for a while... How about 40 moves every 60 minutes or something similar, repeated until the game is drawn or ends normally...
This page took 0.01 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.